JPH024515A - Ink jet head - Google Patents

Abstract

PURPOSE:To improve ink supplying capacity and to accelerate the returning time of an ink meniscus by forming grooves directed toward the center of a nozzle near the inlet opening of ink of the nozzle. CONSTITUTION:A piezoelectric converter 18 is so attached to a nozzle plate 11 through a spacer 15 as to dispose the ends of a plurality of vibrators 91 at positions corresponding to a plurality of nozzles 20 arranged on the plate 11. Radial nozzles 13 directed toward the center of the nozzle are so disposed in the directions of the nozzle array and crossing it near the inlet opening of the ink of the nozzle. The grooves 13 may also be disposed at an angle or 45 degrees to the arranging direction of the nozzle row. Accordingly, after the ink is discharged, even if ink meniscus is largely sucked to the inside of the nozzle, the operation of a capillary tube force in the groove 13 is applied to the meniscus. Thus, the returning time of the meniscus is shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inkjet recording apparatus such as a printer that forms an ink image on a medium such as a recording paper by flying ink droplets, and more particularly to an inkjet printer head.

[Conventional technology]

A nozzle forming member having a plurality of nozzles, a piezoelectric transducer including a vibrator disposed opposite to each nozzle, and ink filling a gap between the piezoelectric transducer and the nozzle forming member and a periphery of the piezoelectric transducer. An on-demand inkjet head that displaces a piezoelectric transducer using an applied voltage and ejects ink from a nozzle is known, for example, from Japanese Patent Publication No. 1986-
This method is disclosed in Japanese Patent No. 8953, and has the advantage that it is highly stable and can operate normally even if foreign matter such as air bubbles or dust gets mixed into the ink without being affected by this.

Further, the gap between the nozzle forming member and the vibrator is configured to maintain a small gap because it has a large effect on the ink ejection characteristics.

[Problem to be solved by the invention]

However, in the conventional inkjet head, by keeping the gap between the vibrator and the nozzle forming member small, the pressure of the ink existing in this gap is increased to obtain the required ejection speed and amount of ink droplets. Because
After ink is ejected, the supply of ink necessary to restore the nozzle meniscus in preparation for the next ink ejection is hindered by the gap between the vibrator and the nozzle forming member, resulting in a long ink return time. Therefore, as the response frequency is increased, ink supply shortages tend to occur, resulting in a decrease in responsiveness and accompanying fluctuations in the amount of ink ejection due to the response frequency.

The present invention is intended to solve these problems, and its purpose is to create an inkjet with excellent responsiveness and ejection stability without giving up on maintaining a sufficient ink droplet ejection speed and amount. The purpose is to provide the head.

[Means to solve the problem]

The inkjet head according to the present invention includes a nozzle forming member having a plurality of nozzles, a piezoelectric transducer including a vibrator arranged opposite to each nozzle, a gap between the piezoelectric transducer and the nozzle forming member, and a piezoelectric transducer. an inkjet head that discharges ink from a nozzle by displacing a piezoelectric transducer by an applied voltage, the inkjet head comprising: ink filling the periphery of the nozzle; It is characterized by being provided with a groove.

[Effect]

According to the above configuration of the present invention, since at least one groove toward the center of the nozzle is provided near the ink inlet opening of the nozzle, the ink meniscus drawn into the inside of the nozzle after ink is ejected flows into the groove. As a result, the capillary force acting on the meniscus becomes stronger, and the return time of the ink meniscus becomes faster.

〔Example〕

The details of the present invention will be explained below using specific examples with reference to the drawings.

FIG. 1 is a perspective view of a printer equipped with an inkjet head according to the present invention, in which a recording medium 1 is wound around a platen 4 by the pressure of feed rollers 2 and 3, and is conveyed in the direction of an arrow 5 as recording progresses. Ru. Guide shaft 6/7
An inkjet head 9 having a plurality of nozzles is mounted on a carriage 8 that is guided by a carriage 8 and movable in a direction parallel to the axis of the platen 4, and as it moves in the direction of an arrow 10, ink droplets are ejected from each nozzle. The ink is ejected to form an ink image on a recording medium.

FIG. 2 is a front view of the inlet opening of the nozzle according to the present invention, and in the vicinity of the inlet opening 12 of a plurality of nozzles 20 arranged in a row on the nozzle plate 11, which is a nozzle forming member,
Radial grooves 13 toward the center of the nozzle 20 are formed by dicing in the arrangement direction of the nozzle rows and in the direction crossing this.

Incidentally, the nozzle shape has a great influence on the ink ejection characteristics, and in order to suppress variations in the ink ejection characteristics between nozzles, the nozzle dimensions require extremely high precision. In this embodiment, the nozzle 20 is formed with extremely high dimensional accuracy by nickel electroforming using a circular thin plate core.

FIG. 3 is a cross-sectional view of the inkjet head equipped with the nozzle plate 11 shown in FIG. 2 for explaining the structure and principle of ejecting ink droplets. The piezoelectric transducer 18 is connected to the nozzle plate 11 via the spacer 15 so that the tips of the plurality of vibrators 19 are arranged at positions corresponding to the plurality of nozzles 20 arranged in a row on the nozzle plate 11.
installed on. The piezoelectric transducer 18 is made of a laminated material of a piezoelectric element 17 and a metal plate 16, and when a voltage is selectively applied, the corresponding vibrator 19 vibrates in a direction perpendicular to the surface of the nozzle plate 11, causing the nozzle plate 11 and the vibrator to vibrate. The ink 14 interposed between the nozzles 19 and 19 is pressed and ejected from the nozzle 20. At this time, in the vicinity of the ink inlet opening of the nozzle according to this embodiment, radial grooves 13 directed toward the center of the nozzle are arranged in the arrangement direction of the nozzle rows and in a direction crossing this, so that after ink is ejected, Even if the ink meniscus is largely drawn to the inside of the nozzle, the capillary force in the groove 13 acts on the ink meniscus, shortening the return time of the ink meniscus.

FIG. 4 is a front view of a nozzle inlet opening for explaining another embodiment of the nozzle shape used in the inkjet head of the present invention. Nozzle 2 in this example
The groove portion 13 near the inlet opening of No. 0 is arranged at an angle of 45 degrees with the arrangement direction of the nozzle rows. Therefore, even if the ink meniscus is largely drawn inside the nozzle after ink is ejected, the capillary force in the groove 13 acts on the ink meniscus, shortening the return time of the ink meniscus, and reducing the amount of ink near the nozzle. Groove 1 in the flow
3 is generated, fluid coupling between adjacent nozzles is reduced, and mutual influence between each nozzle can be reduced.

Although a cantilever-beam vibrator is used as the vibrator in this embodiment, a similar configuration is also possible with a double-beam vibrator.

In the above embodiments, the nozzle has a horn-shaped cross section where the nozzle inlet opening area is wider than the exit opening area, but this does not impose any restrictions on the nozzle shape, and in the present invention, It is clear from the spirit of the invention that any shape may be adopted for the nozzle.

〔Effect of the invention〕

As described above, according to the above structure of the present invention, at least one groove toward the center of the nozzle is provided near the ink inlet opening of the nozzle, which is necessary for restoring the nozzle meniscus after ink is ejected. In addition, the ink meniscus is acted upon by the capillary force in the groove 13, and the return time of the ink meniscus becomes faster. Therefore, even if the response frequency is increased, ink can still be supplied to the nozzles in time, making it possible to improve the responsiveness without sacrificing sufficient ink droplet ejection speed and ejection amount. In this way, it is possible to realize an inkjet head in which characteristics such as ink droplet ejection speed, ejection amount, response, and ejection stability are simultaneously improved.

Further, according to the present invention, it is possible to improve the ink supply capacity simply by forming the grooves by machining such as dicing, so that the manufacturing cost can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a printer equipped with an inkjet head showing one embodiment of the present invention. FIG. 2 is a front view of the inlet opening of a nozzle according to the invention. FIG. 3 is a sectional view of the inkjet head equipped with the nozzle plate shown in FIG. 2 for explaining the structure and principle of ejecting ink droplets. Fourth National Anthem FIG. 4 is a front view of a nozzle inlet opening for explaining another embodiment of the nozzle shape used in the inkjet head of the present invention. 1... Recording medium 9... Inkjet head 11... Nozzle plate 12... Inlet opening 13... Groove portion 14... Ink 18
... Piezoelectric transducer ' 20 ... Nozzle and above Applicant: Seiko Epson Co., Ltd. Representative Patent Attorney Kizobe Suzuki and 1 other person No. 1 Figure 2477, °Nos" I Rare L / - No. 4

Claims (1)

[Claims] A piezoelectric transducer comprising a nozzle forming member having a plurality of nozzles, a vibrator disposed facing each of the nozzles, and a gap between the piezoelectric transducer and the nozzle forming member and a periphery of the piezoelectric transducer. an inkjet head that displaces the piezoelectric transducer by an applied voltage to eject the ink from the nozzle, at least one groove extending toward the center of the nozzle near an ink inlet opening of the nozzle; An inkjet head characterized by: